Bulbs

给你n,m，n是按钮的个数，m是灯泡的总数，然后读入一个数，表示该按钮连接到的灯泡个数，然后输入灯泡个数。判断是否能够通过这些按钮关闭所有的灯

Vasya wants to turn on Christmas lights consisting of $ m $ bulbs. Initially, all bulbs are turned off. There are $ n $ buttons, each of them is connected to some set of bulbs. Vasya can press any of these buttons. When the button is pressed, it turns on all the bulbs it's connected to. Can Vasya light up all the bulbs? If Vasya presses the button such that some bulbs connected to it are already turned on, they do not change their state, i.e. remain turned on.

The first line of the input contains integers $ n $ and $ m $ ( $ 1<=n,m<=100 $ ) — the number of buttons and the number of bulbs respectively. Each of the next $ n $ lines contains $ x_{i} $ ( $ 0<=x_{i}<=m $ ) — the number of bulbs that are turned on by the $ i $ -th button, and then $ x_{i} $ numbers $ y_{ij} $ ( $ 1<=y_{ij}<=m $ ) — the numbers of these bulbs.

If it's possible to turn on all $ m $ bulbs print "YES", otherwise print "NO".

3 4
2 1 4
3 1 3 1
1 2

YES

3 3
1 1
1 2
1 1

NO

In the first sample you can press each button once and turn on all the bulbs. In the 2 sample it is impossible to turn on the 3-rd lamp.